As far as how many days to each month - boy, I didn't know that until
I was an adult. My mom tried to teach me the rhyme, but my version
went like this one I found online:

Thirty days hath September,
All the rest I can't remember.
The calendar hangs on the wall;
Why bother me with this at all?

But when I was in my twenties, my husband showed me the knuckle
calendar. It's easier to show than tell, but here's Wikipedia's
explanation:

You can also use the knuckles of the four fingers of your hand and the
spaces between them to remember the lengths of the months. First make
a fist, then begin listing each month as you proceed across your hand.
All months landing on a knuckle are 31 days long and those landing
between them are not (it's up to you to figure out February). When you
reach the knuckle of your little finger (July), go back to the first
knuckle and continue with August.

For the first time, I could remember without looking at a calendar!

And I've needed to do so maybe a handful of times.

*Maybe* that
many.

I'm quite sure Fisher doesn't know this information. It will come up
in conversation someday, just as it did between my husband and me.